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author | Minteck <contact@minteck.org> | 2022-06-04 08:51:01 +0200 |
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committer | Minteck <contact@minteck.org> | 2022-06-04 08:51:01 +0200 |
commit | 383285ecd5292bf9a825e05904955b937de84cc9 (patch) | |
tree | 0a53b6f02c1604b078044567c03dc1b6c944c8c2 /node_modules/string_decoder/index.js | |
download | equestriadb-383285ecd5292bf9a825e05904955b937de84cc9.tar.gz equestriadb-383285ecd5292bf9a825e05904955b937de84cc9.tar.bz2 equestriadb-383285ecd5292bf9a825e05904955b937de84cc9.zip |
Initial commit
Diffstat (limited to 'node_modules/string_decoder/index.js')
-rw-r--r-- | node_modules/string_decoder/index.js | 221 |
1 files changed, 221 insertions, 0 deletions
diff --git a/node_modules/string_decoder/index.js b/node_modules/string_decoder/index.js new file mode 100644 index 0000000..b00e54f --- /dev/null +++ b/node_modules/string_decoder/index.js @@ -0,0 +1,221 @@ +// Copyright Joyent, Inc. and other Node contributors. +// +// Permission is hereby granted, free of charge, to any person obtaining a +// copy of this software and associated documentation files (the +// "Software"), to deal in the Software without restriction, including +// without limitation the rights to use, copy, modify, merge, publish, +// distribute, sublicense, and/or sell copies of the Software, and to permit +// persons to whom the Software is furnished to do so, subject to the +// following conditions: +// +// The above copyright notice and this permission notice shall be included +// in all copies or substantial portions of the Software. +// +// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS +// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF +// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN +// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, +// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR +// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE +// USE OR OTHER DEALINGS IN THE SOFTWARE. + +var Buffer = require('buffer').Buffer; + +var isBufferEncoding = Buffer.isEncoding + || function(encoding) { + switch (encoding && encoding.toLowerCase()) { + case 'hex': case 'utf8': case 'utf-8': case 'ascii': case 'binary': case 'base64': case 'ucs2': case 'ucs-2': case 'utf16le': case 'utf-16le': case 'raw': return true; + default: return false; + } + } + + +function assertEncoding(encoding) { + if (encoding && !isBufferEncoding(encoding)) { + throw new Error('Unknown encoding: ' + encoding); + } +} + +// StringDecoder provides an interface for efficiently splitting a series of +// buffers into a series of JS strings without breaking apart multi-byte +// characters. CESU-8 is handled as part of the UTF-8 encoding. +// +// @TODO Handling all encodings inside a single object makes it very difficult +// to reason about this code, so it should be split up in the future. +// @TODO There should be a utf8-strict encoding that rejects invalid UTF-8 code +// points as used by CESU-8. +var StringDecoder = exports.StringDecoder = function(encoding) { + this.encoding = (encoding || 'utf8').toLowerCase().replace(/[-_]/, ''); + assertEncoding(encoding); + switch (this.encoding) { + case 'utf8': + // CESU-8 represents each of Surrogate Pair by 3-bytes + this.surrogateSize = 3; + break; + case 'ucs2': + case 'utf16le': + // UTF-16 represents each of Surrogate Pair by 2-bytes + this.surrogateSize = 2; + this.detectIncompleteChar = utf16DetectIncompleteChar; + break; + case 'base64': + // Base-64 stores 3 bytes in 4 chars, and pads the remainder. + this.surrogateSize = 3; + this.detectIncompleteChar = base64DetectIncompleteChar; + break; + default: + this.write = passThroughWrite; + return; + } + + // Enough space to store all bytes of a single character. UTF-8 needs 4 + // bytes, but CESU-8 may require up to 6 (3 bytes per surrogate). + this.charBuffer = new Buffer(6); + // Number of bytes received for the current incomplete multi-byte character. + this.charReceived = 0; + // Number of bytes expected for the current incomplete multi-byte character. + this.charLength = 0; +}; + + +// write decodes the given buffer and returns it as JS string that is +// guaranteed to not contain any partial multi-byte characters. Any partial +// character found at the end of the buffer is buffered up, and will be +// returned when calling write again with the remaining bytes. +// +// Note: Converting a Buffer containing an orphan surrogate to a String +// currently works, but converting a String to a Buffer (via `new Buffer`, or +// Buffer#write) will replace incomplete surrogates with the unicode +// replacement character. See https://codereview.chromium.org/121173009/ . +StringDecoder.prototype.write = function(buffer) { + var charStr = ''; + // if our last write ended with an incomplete multibyte character + while (this.charLength) { + // determine how many remaining bytes this buffer has to offer for this char + var available = (buffer.length >= this.charLength - this.charReceived) ? + this.charLength - this.charReceived : + buffer.length; + + // add the new bytes to the char buffer + buffer.copy(this.charBuffer, this.charReceived, 0, available); + this.charReceived += available; + + if (this.charReceived < this.charLength) { + // still not enough chars in this buffer? wait for more ... + return ''; + } + + // remove bytes belonging to the current character from the buffer + buffer = buffer.slice(available, buffer.length); + + // get the character that was split + charStr = this.charBuffer.slice(0, this.charLength).toString(this.encoding); + + // CESU-8: lead surrogate (D800-DBFF) is also the incomplete character + var charCode = charStr.charCodeAt(charStr.length - 1); + if (charCode >= 0xD800 && charCode <= 0xDBFF) { + this.charLength += this.surrogateSize; + charStr = ''; + continue; + } + this.charReceived = this.charLength = 0; + + // if there are no more bytes in this buffer, just emit our char + if (buffer.length === 0) { + return charStr; + } + break; + } + + // determine and set charLength / charReceived + this.detectIncompleteChar(buffer); + + var end = buffer.length; + if (this.charLength) { + // buffer the incomplete character bytes we got + buffer.copy(this.charBuffer, 0, buffer.length - this.charReceived, end); + end -= this.charReceived; + } + + charStr += buffer.toString(this.encoding, 0, end); + + var end = charStr.length - 1; + var charCode = charStr.charCodeAt(end); + // CESU-8: lead surrogate (D800-DBFF) is also the incomplete character + if (charCode >= 0xD800 && charCode <= 0xDBFF) { + var size = this.surrogateSize; + this.charLength += size; + this.charReceived += size; + this.charBuffer.copy(this.charBuffer, size, 0, size); + buffer.copy(this.charBuffer, 0, 0, size); + return charStr.substring(0, end); + } + + // or just emit the charStr + return charStr; +}; + +// detectIncompleteChar determines if there is an incomplete UTF-8 character at +// the end of the given buffer. If so, it sets this.charLength to the byte +// length that character, and sets this.charReceived to the number of bytes +// that are available for this character. +StringDecoder.prototype.detectIncompleteChar = function(buffer) { + // determine how many bytes we have to check at the end of this buffer + var i = (buffer.length >= 3) ? 3 : buffer.length; + + // Figure out if one of the last i bytes of our buffer announces an + // incomplete char. + for (; i > 0; i--) { + var c = buffer[buffer.length - i]; + + // See http://en.wikipedia.org/wiki/UTF-8#Description + + // 110XXXXX + if (i == 1 && c >> 5 == 0x06) { + this.charLength = 2; + break; + } + + // 1110XXXX + if (i <= 2 && c >> 4 == 0x0E) { + this.charLength = 3; + break; + } + + // 11110XXX + if (i <= 3 && c >> 3 == 0x1E) { + this.charLength = 4; + break; + } + } + this.charReceived = i; +}; + +StringDecoder.prototype.end = function(buffer) { + var res = ''; + if (buffer && buffer.length) + res = this.write(buffer); + + if (this.charReceived) { + var cr = this.charReceived; + var buf = this.charBuffer; + var enc = this.encoding; + res += buf.slice(0, cr).toString(enc); + } + + return res; +}; + +function passThroughWrite(buffer) { + return buffer.toString(this.encoding); +} + +function utf16DetectIncompleteChar(buffer) { + this.charReceived = buffer.length % 2; + this.charLength = this.charReceived ? 2 : 0; +} + +function base64DetectIncompleteChar(buffer) { + this.charReceived = buffer.length % 3; + this.charLength = this.charReceived ? 3 : 0; +} |